Implement NOOP_METHOD_CALL lint
Implements the beginnings of https://github.com/rust-lang/lang-team/issues/67 - a lint for detecting noop method calls (e.g, calling `<&T as Clone>::clone()` when `T: !Clone`).
This PR does not fully realize the vision and has a few limitations that need to be addressed either before merging or in subsequent PRs:
* [ ] No UFCS support
* [ ] The warning message is pretty plain
* [ ] Doesn't work for `ToOwned`
The implementation uses [`Instance::resolve`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/instance/struct.Instance.html#method.resolve) which is normally later in the compiler. It seems that there are some invariants that this function relies on that we try our best to respect. For instance, it expects substitutions to have happened, which haven't yet performed, but we check first for `needs_subst` to ensure we're dealing with a monomorphic type.
Thank you to ```@davidtwco,``` ```@Aaron1011,``` and ```@wesleywiser``` for helping me at various points through out this PR ❤️.
Revert non-power-of-two vector restriction
Removes the power of two restriction from rustc. As discussed in https://github.com/rust-lang/stdsimd/issues/63
r? ```@calebzulawski```
cc ```@workingjubilee``` ```@thomcc```
Add incomplete feature gate for inherent associate types.
Mentored by ``````@oli-obk``````
So far the only change is that instead of giving an automatic error, the following code compiles:
```rust
struct Foo;
impl Foo {
type Bar = isize;
}
```
The backend work to make it actually usable isn't there yet. In particular, this:
```rust
let x : Foo::Bar;
```
will give you:
```sh
error[E0223]: ambiguous associated type
--> /$RUSTC_DIR/src/test/ui/assoc-inherent.rs:15:13
|
LL | let x : Foo::Bar;
| ^^^^^^^^ help: use fully-qualified syntax: `<Foo as Trait>::Bar`
```
Move pick_by_value_method docs above function header
- Currently style triggers #81183 so we can't add `#[instrument]` to
this function.
- Having docs above the header is more consistent with the rest of the
code base.
Improve error msgs when found type is deref of expected
This improves help messages in two cases:
- When expected type is `T` and found type is `&T`, we now look through blocks
and suggest dereferencing the expression of the block, rather than the whole
block.
- In the above case, if the expression is an `&`, we not suggest removing the
`&` instead of adding `*`.
Both of these are demonstrated in the regression test. Before this patch the
first error in the test would be:
error[E0308]: `if` and `else` have incompatible types
--> test.rs:8:9
|
5 | / if true {
6 | | a
| | - expected because of this
7 | | } else {
8 | | b
| | ^ expected `usize`, found `&usize`
9 | | };
| |_____- `if` and `else` have incompatible types
|
help: consider dereferencing the borrow
|
7 | } else *{
8 | b
9 | };
|
Now:
error[E0308]: `if` and `else` have incompatible types
--> test.rs:8:9
|
5 | / if true {
6 | | a
| | - expected because of this
7 | | } else {
8 | | b
| | ^
| | |
| | expected `usize`, found `&usize`
| | help: consider dereferencing the borrow: `*b`
9 | | };
| |_____- `if` and `else` have incompatible types
The second error:
error[E0308]: `if` and `else` have incompatible types
--> test.rs:14:9
|
11 | / if true {
12 | | 1
| | - expected because of this
13 | | } else {
14 | | &1
| | ^^ expected integer, found `&{integer}`
15 | | };
| |_____- `if` and `else` have incompatible types
|
help: consider dereferencing the borrow
|
13 | } else *{
14 | &1
15 | };
|
now:
error[E0308]: `if` and `else` have incompatible types
--> test.rs:14:9
|
11 | / if true {
12 | | 1
| | - expected because of this
13 | | } else {
14 | | &1
| | ^-
| | ||
| | |help: consider removing the `&`: `1`
| | expected integer, found `&{integer}`
15 | | };
| |_____- `if` and `else` have incompatible types
Fixes#82361
---
r? ````@estebank````
fix the false 'defined here' messages
Closes#80853.
Take this code:
```rust
struct S;
fn repro_ref(thing: S) {
thing();
}
```
Previously, the error message would be this:
```
error[E0618]: expected function, found `S`
--> src/lib.rs:4:5
|
3 | fn repro_ref(thing: S) {
| ----- `S` defined here
4 | thing();
| ^^^^^--
| |
| call expression requires function
error: aborting due to previous error
```
This is incorrect as `S` is not defined in the function arguments, `thing` is defined there. With this change, the following is emitted:
```
error[E0618]: expected function, found `S`
--> $DIR/80853.rs:4:5
|
LL | fn repro_ref(thing: S) {
| ----- is of type `S`
LL | thing();
| ^^^^^--
| |
| call expression requires function
|
= note: local variable `S` is not a function
error: aborting due to previous error
```
As you can see, this error message points out that `thing` is of type `S` and later in a note, that `S` is not a function. This change does seem like a downside for some error messages. Take this example:
```
LL | struct Empty2;
| -------------- is of type `Empty2`
```
As you can see, the error message shows that the definition of `Empty2` is of type `Empty2`. Although this isn't wrong, it would be more helpful if it would say something like this (which was there previously):
```
LL | struct Empty2;
| -------------- `Empty2` defined here
```
If there is a better way of doing this, where the `Empty2` example would stay the same as without this change, please inform me.
**Update: This is now fixed**
CC `@camelid`
- Currently style triggers #81183 so we can't add `#[instrument]` to
this function.
- Having docs above the header is more consistent with the rest of the
code base.
This improves help messages in two cases:
- When expected type is `T` and found type is `&T`, we now look through blocks
and suggest dereferencing the expression of the block, rather than the whole
block.
- In the above case, if the expression is an `&`, we not suggest removing the
`&` instead of adding `*`.
Both of these are demonstrated in the regression test. Before this patch the
first error in the test would be:
error[E0308]: `if` and `else` have incompatible types
--> test.rs:8:9
|
5 | / if true {
6 | | a
| | - expected because of this
7 | | } else {
8 | | b
| | ^ expected `usize`, found `&usize`
9 | | };
| |_____- `if` and `else` have incompatible types
|
help: consider dereferencing the borrow
|
7 | } else *{
8 | b
9 | };
|
Now:
error[E0308]: `if` and `else` have incompatible types
--> test.rs:8:9
|
5 | / if true {
6 | | a
| | - expected because of this
7 | | } else {
8 | | b
| | ^
| | |
| | expected `usize`, found `&usize`
| | help: consider dereferencing the borrow: `*b`
9 | | };
| |_____- `if` and `else` have incompatible types
The second error:
error[E0308]: `if` and `else` have incompatible types
--> test.rs:14:9
|
11 | / if true {
12 | | 1
| | - expected because of this
13 | | } else {
14 | | &1
| | ^^ expected integer, found `&{integer}`
15 | | };
| |_____- `if` and `else` have incompatible types
|
help: consider dereferencing the borrow
|
13 | } else *{
14 | &1
15 | };
|
now:
error[E0308]: `if` and `else` have incompatible types
--> test.rs:14:9
|
11 | / if true {
12 | | 1
| | - expected because of this
13 | | } else {
14 | | &1
| | ^-
| | ||
| | |help: consider removing the `&`: `1`
| | expected integer, found `&{integer}`
15 | | };
| |_____- `if` and `else` have incompatible types
Fixes#82361
Suggest `return`ing tail expressions that match return type
Some newcomers are confused by the behavior of tail expressions,
interpreting that "leaving out the `;` makes it the return value".
To help them go in the right direction, suggest using `return` instead
when applicable.
Improve suggestion for tuple struct pattern matching errors.
Closes#80174
This change allows numbers to be parsed as field names when pattern matching on structs, which allows us to provide better error messages when tuple structs are matched using a struct pattern.
r? ``@estebank``
Make "missing field" error message more natural
```rust
struct A {
x: i32,
y: i32,
z: i32,
}
fn main() {
A { };
}
```
```
error[E0063]: missing fields `x`, `y`, `z` in initializer of `A`
--> src/main.rs:8:5
|
8 | A { };
| ^ missing `x`, `y`, `z`
```
This error is now:
```
error[E0063]: missing fields `x`, `y` and `z` in initializer of `A`
--> src/main.rs:8:5
|
8 | A { };
| ^ missing `x`, `y` and `z`
```
I thought it looked nicer and more natural this way. Also, if there is >3 fields missing, there is an "and" as well ("missing \`x\`, \`y\`, \`z\` *and* 1 other field"), but for <=3 there is not. As such it improves consistency too.
As for the implementation, originally I ended up with a chunky `push_str` algorithm but then I figured I could just do the formatting manually since it's just 3 field names at maximum. It is comparatively readable.
As a sidenote, one thing I was wondering about is, isn't there more cases where you have a list of things like field names? Maybe this whole thing can at some point later be made into a more general function to be used in multiple areas.
When a tail expression isn't unit, we previously always suggested adding
a trailing `;` to turn it into a statement. This suggestion isn't
appropriate for any expression that doesn't have side-effects, as the
user will have likely wanted to call something else or do something with
the resulting value, instead of just discarding it.
Some newcomers are confused by the behavior of tail expressions,
interpreting that "leaving out the `;` makes it the return value".
To help them go in the right direction, suggest using `return` instead
when applicable.
Fix panic in 'remove semicolon' when types are not local
It's not possible to check if removing a semicolon fixes the type error
when checking match arms and one or both of the last arm's and the
current arm's return types are imported "opaque" types. In these cases
we don't generate a "consider removing semicolon" suggestions.
Fixes#81839
---
I'm not sure how to add a test for this. I think the test would need at least two crates. Do we have any existing tests that do this so that I can take a look?
Do not ICE when evaluating locals' types of invalid `yield`
When a `yield` is outside of a generator, check its value regardless to
avoid an ICE while trying to get all locals' types in writeback.
Fix#78653.
name async generators something more human friendly in type error diagnostic
fixes#81457
Some details:
1. I opted to load the generator kind from the hir in TyCategory. I also use 1 impl in the hir for the descr
2. I named both the source of the future, in addition to the general type (`future`), not sure what is preferred
3. I am not sure what is required to make sure "generator" is not referred to anywhere. A brief `rg "\"generator\"" showed me that most diagnostics correctly distinguish from generators and async generator, but the `descr` of `DefKind` is pretty general (not sure how thats used)
4. should the descr impl of AsyncGeneratorKind use its display impl instead of copying the string?
Ensure valid TraitRefs are created for GATs
This fixes `ProjectionTy::trait_ref` to use the correct substs. Places that need all of the substs have been updated to not use `trait_ref`.
r? ````@jackh726````
It's not possible to check if removing a semicolon fixes the type error
when checking match arms and one or both of the last arm's and the
current arm's return types are imported "opaque" types. In these cases
we don't generate a "consider removing semicolon" suggestions.
Fixes#81839
remove useless ?s (clippy::needless_question_marks)
Example code:
```rust
fn opts() -> Option<String> {
let s: Option<String> = Some(String::new());
Some(s?) // this can just be "s"
}
```
Add diagnostics for specific cases for const/type mismatch err
For now, this adds at least more information so better diagnostics can be emitted for const mismatch errors.
I'm not sure what exactly we want to emit, so I've left notes there temporarily, also to see if this is the right approach
r? ```@lcnr```
cc: ```@estebank```
Implement RFC 2580: Pointer metadata & VTable
RFC: https://github.com/rust-lang/rfcs/pull/2580
~~Before merging this PR:~~
* [x] Wait for the end of the RFC’s [FCP to merge](https://github.com/rust-lang/rfcs/pull/2580#issuecomment-759145278).
* [x] Open a tracking issue: https://github.com/rust-lang/rust/issues/81513
* [x] Update `#[unstable]` attributes in the PR with the tracking issue number
----
This PR extends the language with a new lang item for the `Pointee` trait which is special-cased in trait resolution to implement it for all types. Even in generic contexts, parameters can be assumed to implement it without a corresponding bound.
For this I mostly imitated what the compiler was already doing for the `DiscriminantKind` trait. I’m very unfamiliar with compiler internals, so careful review is appreciated.
This PR also extends the standard library with new unstable APIs in `core::ptr` and `std::ptr`:
```rust
pub trait Pointee {
/// One of `()`, `usize`, or `DynMetadata<dyn SomeTrait>`
type Metadata: Copy + Send + Sync + Ord + Hash + Unpin;
}
pub trait Thin = Pointee<Metadata = ()>;
pub const fn metadata<T: ?Sized>(ptr: *const T) -> <T as Pointee>::Metadata {}
pub const fn from_raw_parts<T: ?Sized>(*const (), <T as Pointee>::Metadata) -> *const T {}
pub const fn from_raw_parts_mut<T: ?Sized>(*mut (),<T as Pointee>::Metadata) -> *mut T {}
impl<T: ?Sized> NonNull<T> {
pub const fn from_raw_parts(NonNull<()>, <T as Pointee>::Metadata) -> NonNull<T> {}
/// Convenience for `(ptr.cast(), metadata(ptr))`
pub const fn to_raw_parts(self) -> (NonNull<()>, <T as Pointee>::Metadata) {}
}
impl<T: ?Sized> *const T {
pub const fn to_raw_parts(self) -> (*const (), <T as Pointee>::Metadata) {}
}
impl<T: ?Sized> *mut T {
pub const fn to_raw_parts(self) -> (*mut (), <T as Pointee>::Metadata) {}
}
/// `<dyn SomeTrait as Pointee>::Metadata == DynMetadata<dyn SomeTrait>`
pub struct DynMetadata<Dyn: ?Sized> {
// Private pointer to vtable
}
impl<Dyn: ?Sized> DynMetadata<Dyn> {
pub fn size_of(self) -> usize {}
pub fn align_of(self) -> usize {}
pub fn layout(self) -> crate::alloc::Layout {}
}
unsafe impl<Dyn: ?Sized> Send for DynMetadata<Dyn> {}
unsafe impl<Dyn: ?Sized> Sync for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Debug for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Unpin for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Copy for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Clone for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Eq for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> PartialEq for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Ord for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> PartialOrd for DynMetadata<Dyn> {}
impl<Dyn: ?Sized> Hash for DynMetadata<Dyn> {}
```
API differences from the RFC, in areas noted as unresolved questions in the RFC:
* Module-level functions instead of associated `from_raw_parts` functions on `*const T` and `*mut T`, following the precedent of `null`, `slice_from_raw_parts`, etc.
* Added `to_raw_parts`
